An Australian teenager has pleaded guilty to hacking Apple, stealing 90 gigabytes of secure files, and accessing customer accounts.

The 16-year-old broke into Apple's mainframe several times over the course of a year, according to The Age, and stored hacking instructions on his laptop under a folder named "hacky hack hack."

Apple identified and reported the hack to the FBI. It said "at no point during this incident" was personal user data compromised.

An Australian teenager managed to hack Apple, steal 90 gigabytes of secure files, and access customer accounts, a court has heard, according to The Age.

The Australian newspaper reported on the hearing, which took place at a children's court in Melbourne on Thursday, and has prompted Apple into issuing a statement reassuring users that their data is safe.

The Age said the 16-year-old — who cannot be named for legal reasons — broke into Apple's mainframe several times over the course of a year, using a system of "computerised tunnels and online bypassing systems."

He downloaded secure files and accessed customer accounts, using instructions stored on his Apple laptops, seized in a raid on his suburban home, under a folder named "hacky hack hack."

The teenager's lawyer reportedly said he targeted Apple because he is an admirer of the trillion-dollar company and hopes to work for it one day. He is said to be well-known in the international hacking community.

Business Insider has contacted Apple for comment. In a statement to Reuters and The Guardian, the company sought to play down the impact of the hack.

"At Apple, we vigilantly protect our networks and have dedicated teams of information security professionals that work to detect and respond to threats," a spokesman said.

"In this case, our teams discovered the unauthorised access, contained it, and reported the incident to law enforcement. We regard the data security of our users as one of our greatest responsibilities and want to assure our customers that at no point during this incident was their personal data compromised."